THE  DETERMINATION  OF  CELLULOSE 

IN  WOOD 


BY 


WILLIAM  YOUNG  ARMSTRONG 


THESIS 

FOR  THE 


DEGREE  OF  BACHELOR  OF  SCIENCE 


IN 


CHEMICAL  ENGINEERING 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCES 


UNIVERSITY  OF  ILLINOIS 


1922 


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Hv-  5 


UNIVERSITY  OF  ILLINOIS 


DQluM.2Ji-i 


92^ 


THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 


William  Young  Armstrong 


The  Determination  of  Cellulose  Tn  wood 
ENTITLED .. 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
DEGREE  OF  _ _ _ Bach  el  or  _ of  _ _S  ci  e.n  c e_  _ in  _ _C  h_e  mi  d a_l  _ J^n_g  i tie  e_r  i_n  g 


Instructor  in  Charge 


Approved 


7 


HEAD  OF  DEPARTMENT  OF 


Cl 


500181 


Digitized  by  the  Internet  Archive 

in  2016 


https://archive.org/details/determinationofcOOarms 


Table  of  Contents 


Introduction.  1 

Historical  and  Theoretical  Part 2 

Object  of  the  Investigation  9 

Experimental  Part  10 

Method  10 

Discussion  and  Conclusions  16 

Summary  17 

Bibliography  18 


ACKNOWLEDGEMENT 


I wish  to  take  this  opportunity  to  express  my 
sincere  appreciation  to  Dr.  Duane  T.  Englis  and  to  Lewis 
W.  Armstrong  of  the  Kimberly»niark  Paper  Co.,  both  of 
whom  assisted  the  author  throughout  the  investigation  and 
the  preparation  of  this  paper  by  means  of  advice,  favors, 
and  suggestions. 


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INTRODUCTION 

The  determination  of  cellulose  in  wood  has  been  the 

subject  of  considerable  discussion  and  research  in  the  past  twenty- 

five  years,  but  it  was  only  during  the  last*  few  years  that  the  need 

method 

of  a more  accurate  and  rapid  was  felt.  This  need  was  experienced  by 
pulp  and  paper  mill  chemists  where  the  cellulose  content  in  the 
raw  materials  is  a determining  factor  in  the  quality  of  the  product. 
Although  the  yield  of  pure  cellulose  fiber  never  reaches  its  theo- 
retical value  in  the  manufacture  of  pulp  and  paper  because  of  the 
hydrolytic  and  oxidizing  effects  of  the  reagents  used,  this  cellu- 
lose value  enables  the  paper  maker  to  see  how  nearly  his  process 
is  approaching  the  optimum.  Because  of  this  urgent  need,  mill 
chemists  and  investigators  have  set  to  work  to  find  out  if  the 
former  standard  methods  could  be  improved  or  new  ones  discovered. 
Almost  every  mill  at  present  uses  its  own  method  which  is  usually 
some  standard  method  which  has  been  modified  to  suit  the  technique 
of  the  operator. 


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Historical  and  Theoretical 

Because  of  the  meagerness  of  knowledge  in  the  field 
of  wood  chemistry,  the  uncertainty  that  exists  as  to  what  consti- 
tutes wood  cellulose,  and  the  great  variety  of  methods  employed 
in  determining  the  cellulose  in  wood  - none  of  which  give  accurate 
results  that  can  be  checked  by  different  operators,  it  seems  to  be 
appropriate  at  this  time  to  give  a Resume  of  the  work  that  has  been 
done  in  an  endeavor  to  discover  a method  that  will  render  results 
of  cellulose  determinations  in  wood  both  accurate  and  comparable. 

Cross  and  Bevan,  in  their  book  on  ’’Researches  on 
Cellulose  1895  - 1900” , discuss  briefly  the  methods  in  use  at  that 
time  and  come  to  the  conclusion  that  the  method  of  Schulze  - 
prolonged  digestion  with  nitric  acid  with  the  addition  of  chlorate- 
gave  the  nearest  approxamation  of  "actual  cellulose”  in  the  raw 
material.  They  do  not  recommend  their  own  method,  which  is  used 
quite  extensively  at  the  present  time,  because  the  product  formed 
yielded  9%  of  furfural  on  distillation  with  HC1,  showing  that  the 
process  resulted  in  a substance  that  was  not  pure  normal  cellulose. 
Most  of  the  methods  discussed  in  Cross  and  Bevan ’s  book  consist  of 
acid  or  alkaline  treatment  of  the  wood,  yielding  a more  or  less 
complex  mixture  of  celluloses  and  furfuroids. 

Sutermeister  (1),  in  a more  recent  book,  reviews 
some  of  Renker’s  work  on  methods  of  determing  cellulose  (2). 

Renker  concludes,  after  a large  number  of  experiments  with  different 
methods,  "that  there  is  absolutely  no  correct  method  for  determining 
the  cellulose  in  woods  but  that  the  method  of  Cross  and.  Bevan  is  the 


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most  satisfactory" • Other  investigators (Konig  and  Hohn)  do  not  ap- 
prove of  this  process  and  claim  that  only  hydrolysis  followed  by 
oxidation  can  free  the  true  cellulose  from  all  impurities.  Heuser 
and  Sieber  (3),  on  the  contrary,  proved  that  lignin  can  he  completely 
removed  by  chlorination  without  any  oxidation  of  the  cellulose ; that 
is,  cellulose  will  not  be  oxidized  by  the  chlorine  until  all  of  the 
lignin  has  been  removed  and  this  stage  of  the  process  can  easily  be 
detected  because  of  the  characteristic  color  produced  by  sodium 
sulphite  solution  on  lignin  chloride. 

Although  Cross  and  Sevan fs  method  is  used  more  exten- 
sively than  any  others,  there  are  many  particulars  in  the  procedure 
that  render  the  results  of  different  operators  unfit  for  comparison. 
Their  original  method  involved  a preliminary  hydrolysis  with  1# 

NaOH,  but  at  the  present  time  there  is  considerable  doubt  as  to 
whether  that  preliminary  treatment  is  necessary  or  not.  Core  (4), 
after  experimenting  with  three  proposed  methods  for  treating  woods 
previous  to  chlorination,  comes  to  the  conclusion  that  "all  methods 
processes  involving  preliminary  hydrolysis,  either  acid  or  alkaline, 
result  in  a diminished  yield  of  both  & and  total  cellulose" . This 
method,  however,  has  been  severely  criticised  because  of  the  high 
furfural  yield  of  the  residue  which,  according  to  some  investigators , 
can  be  removed  by  hydrolysis  with  dilute  inorganic  acids.  Again  this 
hydrolytic  treatment  has  been  criticised  by  Johnsen  (5)  who  has 
shown  that,  although  furfural  yielding  compounds  are  subject  to 
hydrolysis,  normal  cellulose  is  also  attacked  by  dilute  inorganic 
acids.  After  Schwalbe  and  Johnsen  (6)  found  that  cellulose  heated 
with  a mixture  of  glycerol  and  acetic  acid  did  not  show  any  siyns 


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of  attack,  Hovev  and  Johnsen  proposed  a method  (7)  consisting  of  a 
four  hour  hydrolysis  with  glycerol  and  acetic  acid  at  135  C,  followed 
by  the  subsequent  chlorination.  This  method  proved  to  yiel  a residue 
of  high  purity  because,  according  to  Johnsen,  the  acetic  acid-glycer- 
ol mixture  is  able  to  hydrolyze  lower  carbohydrates  and  the  greater 
portion  of  the  furfural  yielding  substances  without  attacking  the 
cellulose  itsejf.  Mahood,  on  the  contrary,  shows  by  means  of  convinc- 
ing experimental  data(8)  that  the  yield  of  pentosan-free  cellulose 
as  well  as  the  pentosan  content  of  the  cellulose  is  reduced  bv 
preliminary  treatment  with  the  acetic  acid-glycerol  mixture.  Then  if 
the  definition  of  wood  cellulose  is  accepted  as  being  the  residue 
remaining  after  successive  alternate  treatments  with  chlorine  and 
dilute  Na^SOg  solution  until  free  from  lignin  derivatives,  the 
residue  consisting  oft  hexosans,  pentosans,  and  possible  furfural 
yielding  compounds  other  than  pentosans,  this  method  involving 
hydrolysis  with  glycerol  and  acetic  acid  certainly  does  not  give  a 
true  value  for  wood  cellulose. 

It  is  very  evident  from  the  literature  on  the  subject 
that  nothing  definite  has  been  decided  upon  as  to  the  preliminary 
treatment  primarily  because  all  investigators  do  not  know  anf  do 
agree  as  to  what  constitutes  wood  cellulose.  Dore  (4)  submits  a 
definition  of  wood  cellulose  as  being  the  residue  remaining  after 
sucessive  alternate  treatments  with  chlorine  and  Na080osolution 
until  free  from  lignin.  Wise  and  Russell  state  (12),  after  a careful 
survey  of  the  results  on  wood  cellulose  chemistry,  that  the  term 
would  better  be  defined  as  being  the  residue  after  such  a treatment 
with  a correction  applied  for  the  pentosan  and  methyl  pentosan 


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content  of  the  residue.  It  is  an  established  fact  that  the  reidue 
is  not  the  same  as  cotton  cellulose  but,  in  attempting  to  clear  up 
the  confusion  that  exists  as  to  what  constitutes  wood  cellulose. 

Wise  and  Rmssell  (12)  have  verified  the  conclusions  of  other  investi- 
gators that  the  normal  cellulose  of  wood  is  the  same  as  that  of 
cotton.  Only  after  the  exact  composition  of  this  so-called  wood 
cellulose  is  known  can  a method  for  determining  the  cellulose  in  wood 
be  proposed  and  accepted.  Until  such  facts  are  known,  industries 
using  such  determinations  must  make  the  best  of  the  methods  known 
at  the  present  time. 

Considerable  work  has  been  done  to  determine  the  best 
length  of  period  of  chlorination  for  the  wood  fiber.  In  Cross  and  B 
Bevan’s  original  method  (11),  an  initial  chlotination  period  of  one 
hour  was  recommended,  but  at  the  present  time  it  is  a recognized 
fact  that  one  hour  is  too  longj  consequently  their  method  has  been 
modified  to  suit  different  operators,  ^chorger,  during  his  extensive 
work  on  the  "Chemistry  of  Wood" (9),  used  one-half  hour  chlorihation 
periods  or  fractions  thereof  until  the  residue  gave  no  lignin 
reaction.  Dore  (4)  used  periods  of  exposure  to  chlorine  as  being 
20  j-15  -15-10  minutes  respectively.  Mahood  (8)  found  that  five 
one-half  hour  chlorinations  were  required  for  complete  reduction 
following  Cross  and  Bevan’s  procedure.  Renker  (5)  obtained  from 
wood  a residue  that  did  not  give  ant  lignin  reactions  by  repeating 
the  chlorination  six  times  with  a total  exposufce  to  the  gas  of  2.75 
hours.  He  also  concludes  from  his  experiments  that  periods  of  chlor- 
ination should  be  as  short  as  possible.  Sieber  and  Walter  (5)  found 
that  four  chlorinations  with  a total  exposure  of  one  hour  were 


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sufficient  to  remove  all  of  the  lignin  from  the  wood  without  injury 
to  the  cellulose. 

Whatever  the  time  for  exposure,  the  chlorination  in 
each  case  was  followed  by  a thorough  solution  of  the  lignin  deriva- 
tives with  NagSOg  solution  . Although  the  periods  of  chloribation 
differ  considerably  in  each  case,  it  was  agreed  by  all  investigators 
that  the  length  of  the  periods  should  be  as  short  a.s  possible, 
depending  on  the  physical  state  of  the  sample  and  on  the  type  of 
wood. 

In  addition  to  the  different  opinions  as  to  the  nature 
of  the  preliminary  treatment,  if  any  at  all,  and  the  length  of  period 
of  exposure  to  chlorine,  methods  differ  widely  as  to  the  type  of 
apparatus  in  which  the  chlorination  takes  place.  Schorger  (9)  used 
an  apparatus  consisting  of  a jar  with  an  inlet  and  an  outlet  for 
water  and  fitted  with7  a removable  lid.  Into  this  jar  were  placed 
four  beakers  containing  the  sample  of  sawdust.  The  chlorine  was 
allowed  to  flow  into  the  beaker  through  tubes  which  were  fitted 
with  stop  cocks  and  terminated  in  one  main  line  outside  of  the  jar. 
Dore,  in  his  work  on  the  "Determination  of  Cellulose  in  Woods" (^), 
used  the  Sieber  and  waiter  method  with  a unique  type  of  apparatus. 

The  material  was  contained  in  a Gooch  crucible  connected  with  a 
filter  flask. A glass  adapter  capped  over  the  filtration  tube  and 
connected  to  the  chlorine  generator.  Later  Dore  proposed  a vacuum 
method  (10)  in  whichbthe  sample  was  introduced  into  a wide  mouthed 
bottle  or  flask,  the  flask  evacuated,  and  the  sample  saturated  with 
chlorine.  Johnsen  and  Hovey  (7)  suggested  the  use  of  a Gooch  crucible 
fitted  with  a calico  filter  pad  - the  sample  remaining  in  the  cru- 


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- 7 - 

citole  throughout  the  procedure.  Cross  and  Bevan’s  method  as  reviewed 
by  Bean  and  Tower  (11),  was  to  wash  the  fiber  on  a cloth  or  wire, 
squeezed  to  remove  the  excess  water,  and  then  placed  in  a beaker  into 
which  a stream  of  chlorine  was  passed. These  same  investigators,  after 
experimenting  with  many  types  of  apparatus,  adopted  that  of  a small 
perforated  porcelain  filter  plate  in  a five  inch  funnel.  With  this 
it  was  necessary  to  filter  several  times  before  a clear  filtrate 
was  obtained. 

Many  investigators  claim  that  an  apparatus  that  allows 
the  fiber  to  remain  in  the  crucible  or  beaker  throughout  the  operatioi 
is  the  best.  This  may  be  true  but  there  are  several  disadvantages 
of  such  types  in  that  the  fiber  mats  down  tightly  and  does  not  allow 
the  chlorine  to  reach  all  of  the  particles.  Then,  too,  with  a little 
practice,  an  operator  can  handle  an  apparatus  efficiently  that  does 
involve  several  transfers  of  material. 

There  is  one  particular  in  Cross  and  Bevan’s  method 
that  has  not  received  as  much  attention  as  others  but  seems  to  be 
no  less  important.  That  is  the  physical  state  of  the  wood  during 
chlofcination . Cross  and  Eevan  merely  stated  in  their  original  proce- 
dure that  the  wood  must  be  reduced  to  the  "finest  possible  shavings" . 
In  the  mwthod  adopted  by  Dean  and  Tower  (11)  wood  that  sifted  through 
a screen  having  24  meshes  to  the  inch  was  used.  Schorger  used  the 
material  in  two  different  forms  (9)  - sawdust  and  shavings  not  more 
than  0.005  mm.  in  thickness.  These  shavings  were  screened  and  all 
that  passed  through  a 40  mesh  screen  was  rejected.  The  sawdust  was 
ground  to  pass  through  a 40  mesh  screen.  Johnsen  and  Hovey  (7)find 


- s 


that,  in  order  to  reduce  the  time  of  chlorination  to  a minimum,  the 
material  should  he  of  such  fineness  and  uniformity  as  to  pass  through 
an  80  mesh  screen  hut  he  retained  on  a 100  mesh  screen,  Dore(lO) 
used  material  that  passed  through  a 2 mm.  sieve.  In  a mpre  recent 
paper,  Dore  (4)  obtained  a sample  of  sawdust  hy  sifting  it  through 
a 50  mesh  screen.  Mahood  conducted  ah  extensive  study  on  the  "Effect 
of  Size  od  Particle  on  the  Yield  of  Cellulose"  (G)  and  comes  to  the 
conclusion  that  material  which  passes  through  an  80  mesh  seive  hut 
is  retained  on  a 100  mesh  screen  is  the  most  satisfactory  for  cellu- 
lose determinations.  This  material  is  not  representative  of  the  entir 
sample  so  he  recommends  the  combination  of  two  fiorms,  those  from 
sawing  and  grinding.  He  also  concludes  that  the  variation  in  cellu- 
lose content  using  various  sizes  of  paricles  is  due  to: 

1.  Too  wide  a range  in  size  of  particle  in  the  material 
causing  an  attack  on  the  cellulose  of  the  smaller  particles  before 
the  non-cellulose  material  of  the  larger  particles  can  he  removed. 

2.  A possible  fractionation  of  the  materials  due  to  sifting 
out  certain  portions. 


It  is  quite  evident  from  the  experimental  data  of 
several  investigators  that  the  material  of  this  type  is  the  most 
satisfactory  hut  certainly  is  not  representative'.  Table  1 shows  the 
proprotion  of  different  meshes  in  a 100  gram  sample  of  White  Spruce 
sawdust  obtained  by  means  of  a woodworker’s  rasp. 


Table  1 , 


100 

mesh 

2.4# 

80 

»» 

2.4 # 

60 

t» 

10.60# 

40 

H 

41.8# 

20 

t» 

42.8# 

— tr  — 


It  is  obvious  from  this  data  that  to  take  the  80  mesh 
portion  which  is  only  2.4^  of  the  entire  sample  as  being  representa- 
tive of  the  sample  is  a decided  error.  One  way  of  overcoming  this 
difficulty  is  to  grind  the  sawdust  so  that  a larger  portion  of  the 
sample  will  pass  through  the  80  mesh  seive.  As  yet  no  grinding 
apparatus  is  available  that  will  give  such  a sample.  Anothercalter- 
native  is  to  work  out  an  analytical  procedure  that  will  give  consis- 
tent results  on  all  meshes  from  20  to  100  since  this  range  includes 
the  major  portion  of  the  sample. 

Object  of  the  Investigation  . It  is  the  object  of  this  research 
to  study  the  effect  of  size  of  particle  on  the  yield  of  cellulose  frolji 
wood  and  from  the  data  obtained,  attempt  to  formulate  a procedure 
that  can  be  adapted  to  any  size  of  sawdust  between  20  and  100  mesh. 


. 


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- 10  - 

Experimental 

Method*  The  method  used  in  ibis  work  is  that  of  Cross  and 
Bevan  which  has  been  modified  by  the  operators  at  the  Kimberly-Clark 
Paper  Co. 

Sampling.  Samples  are  best  obtained  from  green  wood  but 
if  the  wood  is  dry  it  should  be  soaked  in  watercbefore  using.  The 
wood  is  placed  in  a vise  and  rasped  across  the  grain  with  a woodwor- 
ker’s rasp  to  obtain  the  sample  in  as  fibrous  a condition  as  possible 

The  entire  sample  is  then  dried  at  98  - 100  C.  for  one  hour.  It  is 

then  quartered  and  screened,  the  portion  which  passes  through  a 48 
mesh  wire  and  is  retained  on  an  80  mesh  wire  is  taken  as  the  sample*. 

This  is  again  placed  in  the  drying  oven  at  100  -105  C.  Tot  two  hours. 

One  gram  samples  are  then  weighed  out  and  placed  in  a 500  cc.  casser- 
ole. 

Procedure . Add  200  cc.  of  Vf0  NaOH,  cover  with  a watch 
glass,  and  boil  gently  for  30  minutes,  washing  the  fiber  down  from 
the  sides  of  the  dish  and  keeping  the  volume  constant. 

Filter,  with  suction,  on  a small  perforated  porcelain 
plate  covered  on  both  sides  with  pieces  of  bleached  calico,  placed 
in  a 2 1/2  inch  60’  funnel.  Refilter  until  the  filtrate  is  clear. 

Wah  with  a good  volume  of  hot  water,  suck  dry,  and  loosen  the  fiber 
with  a pointed  glass  rod. 

Attach  to  the  chlorine  generator,  cover  with  a watch 
glass,  and  allow  60  -70  babbles  of  chlorine  per  minute  to  pass 
through  the  fiber.  Allow  this  to  continue  for  one  hour,  loosening  the 
fiber  every  15  minutes  with  a glass  rod. 

* Samples  of  various  sizes  were  used  in  this  work 
varying  from  10  to  100  mesh. 


- 11  ~ 

softer  clilorination,  remove  the  funnel  to  a filter  flask 
anrit  wash  with  hot  water  to  remove  the  HC1  formed  during  chlorination. 

Transfer  the  fibers  from  the  funnel  to  a 500  cc. 
casserole  by  means  of  a wash  bottle  filled  with  150  cc . of  Na^SOg. 
Add  the  remaining  amount  of  MagSOg,  place  on  a hot  plate,  and  bring 
to  a boil.  Add  3 cc.  of  10^  NaOH  and  boil  for  5 minutes 

Again  collect  the  fibers  on  the  filter  plate,  wash 
with  hot  water  until  the  dark  color  is  removed,  suck  dry,  and  loosen 
the  fiber  with  a glass  rod. 

Expose  to  chlorine  as  before  but  this  time  for  only 
30  minutes.  Repeat  the  NagSOg  treatment. 

Repeat  the  chlorination  until  the  fiber  turns  white  on 
being  exposed  to  the  gas.  This  should  happen  after  the  third  exposure 
( 15  minutes ) • 

However,  at  which  stage  of  the  operation  this  does  take 
place,  remove  from  the  generator,  and  wash  with  a large  volume  of 
hbt  water.  Transfer  to  a casserole  and  allow  it  to  stand  under  hot 
water  for  15  minutes. 

Collect  in  a tared  Gooch  crucible,  providecLewith  a 
calico  filter  pad,  wash  with  hot  water,  then  with  25  cc.  of  alcohol 
and  finally  with  the  same  amount  of  ether.  Dry  at  105  C.  for  two  hourf^ 
and  weigh. 

If  the  fqfber  is  not  washed  well  at  all  times,  the  final 
residue  will  have  a dirty  brown  color.  This  takes  place  no  matter 
how  white  the  fiber  is  before  drying. 

The  greatest  error  in  any  method  of  this  type  occurs 
in  transfering  the  fiber  from  onr  container  to  another  but  with 
special  care  and  attention  on  the  part  of  the  operator  this  error 


- 12  - 

can  lbe  prcticallv  eliminated. 


Results.  The  results  of  determinations  on  White  Spruce, 


Balsam, 

Poplar,  and  Hemlock 

are  compiled 

in  Table  2. 

Degree 

White 

Balsam 

Poplar 

Hemlock 

of 

Spruce 

mesh 

8 

67.70 

58.17 

10 

51.78 

56.60 

55.95 

52.09 

51 . 07 

55.72 

54.99 

14 

67.48 

56.86 

20 

56.33 

49.63 

60.03 

55.81 

52.92 

56.83 

49.87 

58.20 

54.41 

49.07 

28 

54.75 

55.48 

40 

48.14 

56.55 

54.95 

52.50 

48.69 

57.48 

57.56 

52.86 

48 

52.18 

52.38 

60 

47.11 

55.43 

50.40 

46.75 

47.01 

56.00 

54.09 

53.57 

80 

51.07 

46.30 

54.65 

51.31 

48.57 

50.8$ 

46.51 

54.43 

47.21 

100 

50.16 

45.38 

54.28 

50.38 

50.98 

45.70 

54.56 

50.86 

Conclusions  and  Discussion 
Samples  of  8,  14,  28,  and  48  mesh  were  used  with  the 
White  Spruce  and  not  with  the  others  because  the  sample  of  Spruce 
was  prepared  at  the  Kimberly-Clark  Paper  Co.,  while  the  others  were 
prepared  at  the  laboratory  at  school. 


foo 


-"IS  - 


No  conclusions  could  be  made  from  the  results  of  the 
cellulose  determination  in  the  Hemlock  because,  due  to  some  incon- 
sistency in  the  sample,  results  could  not  be  obtained  that  would  chec  :: 
within  a reasonable  margin. 

Plotting  the  degree  of  mesh  as  abscissa  and  the  per  cen 
of  cellulose  as  ordinates,  curves  1,  2,  and  3 were  drawn.  It  is  evi- 
dent from  these  curves  that  the  per  cent  of  cellulose  varies  with  the 
mesh  according  to  some  certain  equation  (the  equation  of  the  curve). 
Assuming  that  these  curves  are  correct  for  TThite  Spruce,  Balsam,  and 
Hoplar,  it  seems  logical  to  conclude  that  the  per  cent  of  cellulose 
of  any  mesh  could  be  changed  to  some  standard  mesh  - for  instance  80 
mesh  - by  applying  the  correction  factor  of  the  curve.  This  would  not 
aid  in  obtaining  a more  representative  sample  but  it  certainly  would 
render  the  results  of  different  operators  more  comparable  than  they 
are  under  the  methods  used  at  the  present  time. 

It  is  to  be  noted  in  Curve  1 that  the  per  cent  of 
cellulose  is  in  a steady  decrease  from  8 to  50  or  60  mesh  and  from 
there  on  it  is  practically  constant.  It  is  for  that  reason  that  most 
modern  methods  recommend  the  use  of  sawdust  that  paeees  through  an 
80  mesh  screen  but  is  retained  on  a 100  mesh  seive.  Never-the-iess , 
a sample  of  that  size  is  not  representative  of  the  entire  portion  of 
sawdust  (see  Table  1).  It  is  true  that  a portion  of  the  8 or  14  mesh 
size  is  too  large  because,  in  order  to  remove  all  the  lignin  from 
the  larger  particles,  the  entire  sample  must  be  subjected  to  such 
a long  chlorination  that  the  smaller  pafcticles  will  be  oxidized  to 
oxy-celluloses  which  are  soluble  in  Nar,SQ3.  According  to  the  curve 
the  per  cent  of  lignin  remived  in  proportion  to  the  entire  sample 


, 


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increases  to  some  point  "between  50  or  60  mesh  . At  this  place  some 
change  evidently  takes  place  which,  as  yet,  has  not  been  investigated 
but  it  is  probably  o point  representing  the  size  of  particle  which  is 
of  such  a small  and  uniform  size  that  more  or  all  of  the  lignin  is 
removed  in  the  same  time  a smaller  percentage  was  removed  in  the 
larger  meshes.  At  the  same  time  it  must  be  remembered  that,  even  with 
the  larger  meshes,  the  chlorination  was  continued  until  the  addition 
of  NagSOg  solution  to  the  sawdust  did  not  give  the  characteristic 
color  of  lignin  derivatives. 

Considering  these  two  conflicting  statements,  the 

questions  arise:  Is  all  of  the  lignin  removed  from  sawdust  of  a large 

mesh  (10-^C)?  Why  is  not  the  cellulose  value  of  the  8 or  10  mesh 

portion  just  as  representative  of  the  entire  sample  as  is  the  80  -100 

not 

mesh?  If  all  the  lignin  is*  removed,  the  residue  should  give  the  char- 
acteristic colorwith  chlorine  and  Na2S0g  but  all  of  the  samples  were 
chlorinated  to  a point  where  further  chlorination  or  the  addition  of 
NagSOo  solution  produced  no  color.  But  since  the  cellulose  content 
decreases  steadily  from  8 to  50  or  60  mesh,  it  seeme  reasonable  to 
beleive  that  something  besides  lignin  is  being  removed  between  those 
margins  or  else  the  less  resistant  celluloses  are  being  oxidized  to 
substances  that  are  soluble  in  NagSO^,. 

Curve  2,  that  of  Balsam,  does  not  have  exactly  the  same 
shape  as  doed  the  one  for  White  Spruce  probably  because  of  the  inhe- 
rent characteristics  of  the  two  woods.  The  decrease  in  cellulose 
content  with  the  decrease  in  mesh  is  much  slower  and  does  not  come 
to  smell  a constant  value  as  does  the  White  Spruce,  although  the  per- 
centages of  the  80  and  100  mesh  portions  of  Balsam  are  not  more  than 


- 


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- 15  - 

Vf0  apart. 

Curve  3,  that  of  Poplar,  is  practically  the  same  as  that 
of  White  Spruce  except  for  the  peak  that  occurs  at  20  mesh  instead 
of  10.  A possible  explanation  for  that  feature  is  that,  due  to  the 
fibrous  character  and  nonuniformity  of  the  sample  between  the  meshes 
of  10  and  20,  the  sample  of  10  mesh  required  a longer  chlorination 
period  than  others  and  consequently  more  of  the  cellulose  would  have 
destroyed  in  order  to  produce  a residue  free  from  lignin.  Then  the 
sample  of  20  mesh,  being  more  uniform  than  the  10,  would  require  a 
shorter  time  for  chlorination  and  consequently  less  cellulose  would 
be  oxidized  to  oxy-celluloses  or  other  compounds  that  are  soluble  in 
Na^SC^  solution.  The  other  part  of  curve  3 is  practically  the  same 
as  curve  1,  the  cellulose  content  decreasing  steadily  until  about  60 
or  70  mesh  where  the  cellulose  value  reaches  a constant  mark. 

Cellulose  determinations  were  also  run  on  Hemlock  but 
because  results  could  not  be  obtained  that  would  check  within  a 
reasonable  margin  the  curve  for  that  wood  was  not  drawn. 

Throughout  the  discussion  of  these  results  the  " cellu- 
lose content”  or  "cellulose  value”  will  be  referred  to  as  being  the 
per  cent  of  residue  from  the  original  sample  - the  residue  being 
obtained  by  successive  alternate  treatments  with  chlorine  and  Na^SOg 
solution  untij.  free  from  lignin  but  without  any  correction  for  the 
pentosan  or  methyl  pentosan  content  of  the  residue. 

It  is  regretted  that  the  residues  after  each  chlorinatio  i 
could  not  be  analyzed  for,  if  such  data  was  compiled  with  that  alread  r 
collected  during  this  work,  a more  thorough  and  accurate  explanation 
pf  the  curve  s_aoiil^.  be  no  s s tble  ._H  o wey  er.  n each  if,  is  vpi-v 


. 


. 


• 

t 

t 

■ 

- 

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t 

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‘ 

. 

- 


■ 


. 

* 

. 


, 


- 18  - 

evident  that,  although  all  of  the  lignin  was  removed  in  each  case, 
the  cellulose  content  decceased  with  the  decrease  in  size  of  particle 
in  all  woods  that  were  used  in  this  work. 

Mahood’s  conclusion  (4)  that  ” the  material  which  passes 
through  an  80  mesh  screen  and  is  retained  on  a 100  mesh  screen  is 
the  most  satisfactory  for  cellulose  determinations”,  is  correct. 

Such  a sample  is  the  most  satisfactory  in  that  it  requires  shorter 
periods  of  chlorination}  hut  to  take  such  a sample  as  being  represen- 
tative of  the  entire  quantity  of  sawdust  sampled  when  the  results  of 
this  investigation  show  that  coarser  sawdust  is  just  as  free  from 
lignin  hut  has  higher  cellulose  values  than  the  smaller  sawdust, 
does  not  appear  to  he  justifiable.  Conclusions  as  to  the  correct 
mesh  of  sawdust  to  use  in  cellulose  determinations  can  he  made  only 
af&fcr  the  exact  composition  of  ’’wood  cellulose”  and  the  residues 
after  each  chlorination  are  known.  Such  conclusions  must  await  the 
results  of  the  investigators  of  today  who  are  attempting  to  establish 
a complete  and  accurate  knowledge  of  the  chemistry  of  wood  cellulose 
and  until  sue#  facts  are  known,  paper  mills  and  other  industries 
using  cellulose  determinations  should  use  considerable  discretion  in 
the  method  used. 


. 


' 


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< 

. 

. 


. 

. 

. 

- 

- 17  - 

Summary 

1.  The  previous  work  on  the  subject  of  "Determination 
of  Cellulose  in  Wood"  has  beem  reviewed. 

2.  The  cellulose  content  of  White  Spruce,  Balsam,  Poplar 
and  Hemlock  has  been  determined  by  the  Cross  and  Bevan  method  using 
samples  of  at  least  six  different  meshes  varying  in  size  from  10  tp 
100  mesh. 

3.  Curves  for  the  woods  used  have  been  drawn,  plotting 
the  degree  of  mesh  against  the  cellulose  content  of  the  wood  at  that 
raesh . 

4*  From  the  experimental  work  compiled  during  this 
investigation  it  seems  justifiable  to  conclude  that  the  curves  for 
White  Spruce,  Balsam,  and  Hemlock/  plotting  the  degree  of  mesh 
against  the  per  cent  cellulose  at  that  mesh,  afford  a means  of  com- 
paring the  results  of  cellulose  determinations  from  different  opera- 
tors who  use  procedures  involving  the  use  of  sawdust  of  various  sizes 


, 

. 

• 

. 

• 

. 

< 


, 

- . 


- is  - 


BIBLIOGRAPHY 


(1) 

Cross  and  Bevan 
Suterraeister 

Researches  on  Cellulose  139 
Chemistry  of  Pulp  and  Paper 

(2) 

Renker 

Uber  Bestimmungsmethoden  der 

(3) 

Z.  angew.  Chem. 

26  (1913)  S3D1 

(4) 

J.I .E .C  . 

12  (1920)  264 

(5) 

J.I.E.C. 

13  (1921)  359 

(6) 

Pulp  & Paper  Mag 

. of  Can.  13  (1915)  600 

(?) 

J.S.C.I . 

37  ( 1918)  132 

(3) 

J.I.E.C. 

12  ( 1920)  S73 

(9) 

J.I.E.C. 

9 ( 1917)  556 

(10) 

J.I.E.C. 

11  (1919)  556 

(11) 

J »A»C  »S. 

29  (1907)  1119 

(12) 

J . 53 . E . C . 

14  (1922)  285 

UNIVERSITY  OF  ILLINOIS-URBAN  A 


